Conventionally, an electric kettle comprises a vessel in a lower portion of which an electrical element is located. The element and accompanying electrical control circuitry are usually mounted on a side or base wall of the vessel. Typically the element passes through an aperture in the side wall and projects into the vessel. Suitable sealing means are used to ensure a water tight joint between the element and the wall of the vessel to prevent leakage of water in use.
A disadvantage of such an arrangement is that it is not possible to heat a small quantity of water, such as a single cupful, efficiently because an air gap may be left between the upper surface of the water and the element above it. In addition, it is also essential if a sheathed coiled wire electrical element is used that the element is completely covered by water to prevent the element from overheating in use.
Similarly, even in kettles fitted with planar elements which are incorporated into the base of the vessel, it is usual to provide a channel around the periphery of the element in which water remains after the element has been switched off by a safety switch. This again renders the kettle inefficient when only small quantities of heated water are required because more water must be heated than is actually required for use.
It is an object of the present invention to provide a liquid heating apparatus which overcomes or substantially mitigates the aforementioned disadvantage.